Method of drying printed or laminated sheets and webs of paper



United States Patent 3,488,859 METHOD OF DRYING PRINTED 0R LAMINATEDSHEETS AND WEBS OF PAPER Elmar Messerschmitt, Munich, Germany, assignorto Schnellpressenfabrik Frankenthal, Albert 81 Cie Aktiengesellschaft,Frankenthal, Pfalz, Germany, a corporation of Germany No Drawing. FiledNov. 25, 1968, Ser. No. 778,773 Claims priority, application Germany,Nov. 25, 1967, 1,729,465 Int. Cl. F26b 7/00 US. Cl. 34-15 2 ClaimsABSTRACT OF THE DISCLOSURE A method of drying printed or laminatedsheets and webs of paper whereby warm and cold air is appliedalternately to the materials to be dried along air zones in closesuccession. Moreover, the intensity of the applied air and the rate ofsuccession of the warm and cold air zones is adjustable so that noappreciable change in moisture takes place to cause any undesirableshrinkage in the paper web or sheets.

This invention relates to a method of drying printed or laminated sheetsand webs of paper by means of a stream of air.

Under conventional methods, printed Webs of paper are dried by applyinga stream of air onto the webs by means of air nozzles. In thisconventional method, Warm air is applied to the web for a longer thannormal period of time. Thereafter, the web of paper is cooled down toroom temperature by either applying cold air, or by means of rollers.The web of paper may also be heated by guiding it over heated drums.

In all of these drying methods, changes occur in the properties of thepaper which result in shrinking of its sheets or webs. Moreover, whenplastic foils are printed, changes in the properties of the foil willalso occur when these conventional drying methods are used.

These changes in the aper properties are caused by a change in thedampness of the printed material, the webs of paper, or the foils.

If the web of paper is dried by means of air, or by means of dryingdrums, a portion of the water in the paper evaporates so that shrinkingsets in. The same event also occurs when other materials are used, suchas foils, etc.

In order to overcome these disadvantages, one method has attempted todry the paper with unheated air or cold air. However, the drying effectof the cold air has been found to be too weak for drying the papersufliciently when the sheets and the webs of paper are moved rapidly.

It is, therefore, an object of this invention to overcome the aboveidentified disadvantages by providing a method whereby hot and cold airis alternately applied to the paper.

In the direction of the paper movement, warm and cold air zones areapplied to the paper in close succession, whereby the succession and theintensity of the applied air are adjustable. This invention has the advantage, for example, that a printed sheet of paper which is introducedinto the novel drying device is not heated, so that only the printingink on the surface of the sheet of paper is dried.

Since the rather volatile solvents in the printing ink evaporate in ashorter period of time than the parts of water in the paper, the dryingprocess is much more effective.

In this invention, the printing ink is alternately heated and cooled ina short period of time on the surface of the printed material, so thatthe solvent agents in the ink are evaporated in a pulsating fashion. Dueto the short period of time under which drying takes place, and the factthat the air intensity is adjustible, evaporation of any appreciablemoisture percentage in the paper material can thus be avoided. Inaddition, the succession of the warm and/or cold air zones may also beadjusted, i.e., two cold air zones may be adjusted in succession.

Since the moisture percentage of the paper material is not changed whenapplying this method, no shrinking occurs, and therefore, there are nochanges in the properties of the paper.

While only a few embodiments of the present invention have beendescribed, it will be understood that many changes and modifications maybe made thereunto without departing from the spirit and scope of theinvention as defined by the appended claims.

What is claimed is:

1. A method of drying materials in motion such as printed, and laminatedsheets and webs of paper by means of an air stream, comprising the stepsof;

applying warm and cold air alternately to the materials to be dried, inclose succession,

varying the intensity of the applied air, and

adjusting the rate of succession of said warm and cold air applications.

2. The method as recited in claim 1 wherein said step of applyingadditionally comprises the step of directing said hot and cold air alongzones in the direction of motion of said paper material.

References Cited UNITED STATES PATENTS 273,013 2/1883 BedfOrd 34-62 X1,768,455 6/1930 Gibson 34-66 2,469,270 5/1949 Liebel 34-66 2,807,0969/1957 Kellgren 34-66 2,807,097 9/ 1957 Kellgren 34-66 2,952,078 9/1960Litzler 34-66 2,955,342 10/ 1960 Litzler 34-66 3,065,551 11/1962 Cohn34-62 3,318,018 5/1967 Steele 34-62 WILLIAM J. WYE, Primary Examiner US.Cl. X.R. 34-20, 62

